So I was racing yesterday in the FOX then went to a XFR and the sound difference is totally different (as it should be). But when I autoX or goto a trackday (in real life) I do it with my windows down.

I am suggesting an option to have windows down or have the option of either. I understand that it may force the car bodies to be redone but with an open window it allows you to have a better sense of a tire squeeling from slip or how far you are from the wall cause you can hear the echo of your engine.

Windows down is bad for aerodynamics so irl you would always race with windows up.

I think your suggestion is nice, but not important.

Not exactly what you wanted, but are you aware that you can adjust the cockpit muffling in Shift-A? This is a slider which could be equated to a window position.